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<h1>Glueing Cocobolo</h1>

<p>Cocobolo and many other hardwoods such as Lignum Vitae, African Blackwood, Thuja, contain oil. Cocobolo seems to be one of the most oily species, which makes it nearly water proof. Also, it polishes to a very nice shine. On the other hand, this oil creates a lot of problems, when it comes to gluing and finishing. Most glues require oil and grease free surfaces.</p>

<h2>Wiping With Solvents</h2>

<p>A first step to prepare <em>very oily</em> pieces for glueing is wiping the surface with solvent and a cloth or paper towel. The cloth soaks up excessive oil, and will be stained to a strong orange color.</p>

<p>Applicable solvents: Acetone, Turpentine, Naphta, nitro paint thinner.</p>

<p>Reported problems: The wood does not stop bleeding oil, sometimes the problem gets even worse. I have not seen the process in person, but I guess, the solvent was applied directly to the wood so that it penetrated into the wood and thinned the oils inside. A better way might be to apply not too much solvent on the cloth, and then wipe the surfaces.</p>

<p>My guess is to begin with wiping overly excessif surface oil with sparse application of solvents on the cloth first, then switch to sanding.</p>

<p>Note that removing too much oil may change the wood color. Drowning Cocobolo in acetone has been reported to bleach the wood significantly.</p>

<h2>Using Paint Stripper</h2>

<p>Another working tip I found was the application of glue stripper in the preparation step. Similarly to the solvent/wiping method, surface oil is bound, perhaps chemically modified, and then removed with the stripper.</p>

<h2>Sanding the Glueing Surfaces</h2>

<p>Others report that it is sufficient to properly sand the glueing surfaces with 80, up to 220 grit sandpaper. Use new, sharp sandpaper in the final pass: The purpose is to roughen up the surface uniformly, not to get a shiny finish. </p>

<p>Scratching is also mentioned in some places. Obviously, the purpose is to enlarge the microscopic glueing surface.</p>

<p>Clean off the sanding dust with (oil-free!!!) pressure air. The dust binds oil particles, which will be removed also. This should get you a clean, dry glueing surface. Don't wipe with solvents at this point! This will only transport oils form other surfaces, and from your hands, to the glueing surface, and thus neglecting your work. See <a href="http://www.messerforum.net/archive/index.php/t-32288.html">this link</a> for more information: Oil distributes itself <em>immediately</em> on a solvent. To make that apparent, put a little drop of oil on a large water (or solvent) surface: The oil drop rapidly expands to a very thin film, covering a large surface.<p>

<p>Glue immediately after sanding, before more oil from the inside diffuses to the surface. Glue with standard Titebond. </p>

<p>A butt-joined test piece is reported to hold after 4 years by only using the sanding procedure (no solvent-based preparation). The sanding dust seems to bind the surface oils.</p>

<h2>Specialized Glues</h2>

<p>Some people recommed to use Epoxy instead of Titebond. Remember, in contrast to Titebond glue joints, you only need light pressure on the pieces while the Epoxy cures. You need a thin Epoxy film to remain between the pieces. Epoxy has pore filling capabilities.</p>

<p>Recommended Epoxy systems: Uhu Plus, </p>

<p>Two component glues on Methacrylate basis (with a powder hardener), such as Stabilit Express, make problems: The wood oil diffuses into the glue and changes the resin/hardener ratio, so that the polymerisation cannot properly finish (<a href="http://www.messerforum.net/archive/index.php/t-38559.html">www.messerforum.net</a>). Epoxy systems with liquid (acid based) hardeners don't have these problems. Faster and/or lower viscostiy Epoxy systems are generally better. Also, moderate heat up to 60 to 80 &deg; Celsius may help. No hotter, otherwise the wood will sweat out more oil from inside.</p>

<p>Another variant is PU glue.</p>

<h2>Side Notes</h2>

<p>Finishing may change the color significantly:</p>





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